The efficiency of supplemented diets with dicalcium phosphate' (DCP) and phytase (500 and 1000 units) replaced with dietary fish meal instead of soybean meal or full fat soybean at two replacing levels of 50% or 75% for Nile tilapia was investigated.The results of Nile tilapia (initial weight 12.10 ± 0.6 gm) revealed that the average growth performance of fish fed diet supplemented with phytase (500 and 10C0 units) had improved feed conversion ratio and specific growth rate. However, it was also shown that the replacing 50% of the fish meal with soybean meal or soybean full fat in tilapia diet were successful and had no adverse effect on growth.The diet supplemented with DCP or phytase (500 or 1000 units) significantly (PO.01) increased body protein content, body fat, body ash and calcium concentration in both vertebral column and the whole body than control. An inverse relationship between phytase dose and fat content was seen in the present results. However, fish fed the control diet or diet contained 50% of the protein from either soybean full fat or soybean meal gave the highest body protein content, crude ash and the lowest value of ether extract and gross energy content. Calcium content of whole body was higher in the fish fed the control diet than in fish fed any diet containing plant protein sources. The same trend was observed for calcium in the vertebral column.